The present invention relates generally to electrical switches, and more particularly to a hermetically sealed electrical switch assembly having a low manufacture cost.
In conventional electrical switches, especially those used in power circuits, the contacts are exposed to air. Corrosion of the components of these kinds of switches is liable to occur after the switches are used for a period of time, resulting in a poor sensitivity of the switches. In addition, such switches are not suitable for use in dust, moist, easily explosive or combustible environments. Several different types of switches for preventing explosions have been developed, such as oil switches, safety switches, and so forth. However, due to the complex structures of these switches, they are unpractical from a manufacturing standpoint. Accordingly, the inventors disclosed two types of automatic magnetic switches in the U.S. Pat. Nos. 4,739,291 and 5,777,536. The structures of these switches are simper than the conventional switches but still too complicated for manufacture. They are thus desirable to be further improved on the structures thereof.
It is therefore a primary object of the invention to provide a hermetically sealed electrical switch assembly, which is capable of being made to be waterproof, corrosion-proof, dustproof and explosion-proof to provide a more sensitive and safer operating.
Another object of the invention is to provide a simple hermetically sealed electrical switch assembly, which has a lower manufacture cost.
According to the present invention, the hermetically sealed electrical switch assembly comprises a casing having an opening end, a cover sealingly attached to said opening end of said casing to define a primary volume hermetically sealed from external environment, switch means received in said primary volume, magnetic responsive means arranged inside said primary volume, and magnetic activating means attached to the upper surface of said cover for effecting the movement of said magnetic responsive means. The switch means comprises electrical contacts to change the conducting state of a power circuit with which said switch means is connected. and a switching lever which can change its positions according to the conducting state of the power circuit. The magnetic responsive means couples with said switching lever for moving with it.
When the circuit said electrical switch assembly connected is in an over-loaded or short-circuit state, said switching lever of said switch means will switch automatically from a first (ON) position to a second (OFF) position. In the meantime, said magnetic responsive means will be forced by said switching lever to slide to the same way and said magnetic activating means will be forced to slide synchronously by the magnetic attractive force therebetween.
When said switch assembly is desired to be reset after the circuit is opened, User can push said magnetic activating means manually to force sliding to original position. In the meantime, said magnetic responsive means will slide synchronously to the same way by the magnetic attractive force and said switching lever will be forced to switch to the ON position.